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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

37262 results found.

  1. EP 250427a: BOOTES-7 optical afterglow candidate
  2. GRB 250424A: Swift-BAT refined analysis
  3. GRB 250424A: SVOM/GRM observation of a long burst
  4. GRB 250424A: PRIME near-infrared detection
  5. GRB 250424A: WINTER J-band detection
  6. GRB 250424A: EIRSAT-1 GMOD Detection
  7. GRB 250424A: SVOM/VT optical observation
  8. GRB 250419A: Mondy Optical Observations
  9. GRB 250424A: Swift/UVOT Detection
  10. Konus-Wind detection of GRB 250424A
  11. GRB 250424A: Skynet Optical Observations
  12. GRB 250424A: Kilonova-Catcher optical afterglow detection
  13. GRB 250419a: Continued Liverpool Telescope observations
  14. GRB 250419A: Liverpool Telescope optical upper limit
  15. GRB 250407A: GRBAlpha detection
  16. GRB 250404A / EP250404a: GRBAlpha detection
  17. GRB 250330B: GRBAlpha detection
  18. GRB 250419A: SVOM/ECLAIRs refined analysis
  19. GRB 250424A: Swift-XRT refined Analysis
  20. GRB 250424A: Enhanced Swift-XRT position
  21. GRB 250424A: AstroSat CZTI detection of a bright long burst
  22. GRB 250424A: COLIBRÍ Detection of a Bright Optical Counterpart
  23. GRB 250424A: BlackGEM optical afterglow detection
  24. GRB 250424A: VLT/X-shooter spectroscopic redshift z = 0.310
  25. GRB 250424A: likely host galaxy
  26. GRB 250424A: DDOTI Afterglow Detection
  27. GRB 250424A: REM optical/NIR afterglow detection
  28. GRB 250424A: Swift detection of a burst with an optical counterpart
  29. Swift GRB 250424A: Global MASTER-Net observations report
  30. Swift GRB 250424A: Global MASTER-Net OT detection
  31. EP250421a: Nickel optical upper limit
  32. EP250416a / GRB 250416C: Gemini GMOS-S likely host galaxy redshift z = 0.963
  33. EP250421a: Upper limits from Fermi-GBM Observations
  34. SVOM/sb25042207: GOTO optical upper limits
  35. GRB 250421A: AstroSat CZTI detection
  36. GRB250419A: VLA radio detection
  37. GRB 250419A: Mephisto Multi-band Optical Detection
  38. GRB 250419A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  39. GRB 250419A: Optical Observations via Virtual Telescope Project
  40. GRB 250419A: Mondy Continued Optical Observations
  41. Fermi GRB 250421A: Global MASTER-Net observations report
  42. GRB 250421B: AstroSat CZTI detection of a bright long burst
  43. EP250421a: Mephisto optical counterpart confirmation
  44. The EP-WXT trigger 01709135179: Kinder optical counterpart candidate
  45. GRB 250421A: Fermi GBM Final Real-time Localization
  46. GRB 250419A: Liverpool Telescope observations
  47. GRB 250419A: LCO optical observation
  48. GRB 250419A: JinShan optical observations
  49. GRB 250419A: SVOM/VT optical continuous observations
  50. GRB 250419A: SVOM/C-GFT optical observations
  51. GRB 250419A: Swift/UVOT Follow up
  52. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  53. GRB 250419A: LCO optical afterglow multi-band observations
  54. GRB 250419A: Mondy and AbAO Optical Observations
  55. GRB 250419A: Liverpool Telescope observations
  56. GRB 250419A: AKO Optical Afterglow Detection
  57. GRB 250419A: MASTER optical afterglow observation
  58. GRB 250407A: rest-frame energetics from Konus-Wind observation
  59. GRB 250419A: Swift-XRT localisation
  60. GRB 250407A: GTC/OSIRIS+ spectroscopic redshift z = 1.36
  61. GRB 250419A: VLT/X-shooter spectroscopic redshift z = 0.845
  62. GRB 250419A: Swift-XRT refined Analysis
  63. GRB 250419A: GOTO optical counterpart detection
  64. GRB 250419A: KAIT optical afterglow observations
  65. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  66. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  67. GRB 250419A: SVOM detection of a soft burst
  68. Konus-Wind detection of GRB 250416C (a counterpart of EP250416a)
  69. EP250416a: Swift/XRT counterpart fading
  70. EP250416a: refined EP-WXT and EP-FXT analysis
  71. Konus-Wind detection of GRB 250403A
  72. GRB 250403A: VLT/FORS2 spectroscopic redshift z = 1.847
  73. SVOM/sb25041603 is not a GRB
  74. Fermi Gamma-ray Burst Monitor trigger 766505186/250416588 (GRB 250416A) is not a GRB
  75. Fermi Gamma-ray Burst Monitor trigger 766511207/250416657 is not a GRB
  76. GRB 250416B: Fermi GBM Final Real-time Localization
  77. GRB 250416A: Fermi GBM Final Real-time Localization
  78. Fermi Gamma-ray Burst Monitor trigger 766474855/250416237 is not a GRB
  79. GRB 250413A: AstroSat CZTI detection
  80. EP250304a: ATCA radio observations
  81. GRB 250412A: AstroSat CZTI detection
  82. GRB 250411A: DDOTI Optical Observations
  83. Fermi GRB 250411A: Global MASTER-Net observations report
  84. GRB 250411A: Fermi GBM Final Real-time Localization
  85. GRB 250407A: Continued KAIT/Nickel optical observations
  86. GRB 250314A: e-MERLIN observations
  87. GRB 250407A: Mondy and AbAO Optical Observations
  88. GRB 250320B: cubesat Avion detection
  89. IPN triangulation of GRB 250321D (consistent with the fast X-ray transient EP250321a)
  90. IPN triangulation of GRB 250407A
  91. GRB 250407A: LCO detection of a fading optical counterpart
  92. EP250407a: Swift-XRT observations
  93. Konus-Wind detection of GRB 250407A
  94. GRB 250407A: SVOM/GRM observation of a bright long burst
  95. GRB 250407A: EP-WXT afterglow detection
  96. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  97. GRB 250407A: KAIT Optical Afterglow Candidate
  98. GRB 250407A: Fermi GBM Detection
  99. GRB 250407A: Swift-XRT afterglow detection
  100. Fermi GRB 250407A: Global MASTER-Net observations report

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